The sample is placed into a special dish or tube and allowed to grow in the laboratory. Cells are later taken from the new sample and stained. The laboratory specialist uses a microscope to examine the size, shape, and number of chromosomes in the cell sample. The stained sample is photographed to show the arrangement of the chromosomes. This is called a karyotype.

Certain problems can be identified through the number or arrangement of the chromosomes. Chromosomes contain thousands of genes that are stored in DNA, the basic genetic material.

How to Prepare for the Test

Follow the health care provider's instructions on how to prepare for the test.

How the Test will Feel

How the test will feel depends on whether the sample procedure is having blood drawn (venipuncture), amniocentesis, or bone marrow biopsy.

Why the Test is Performed

This test can:

Count the number of chromosomes

Look for structural changes in chromosomes

This test may be done:

On a couple that has a history of miscarriage

To examine any child or baby who has unusual features or developmental delays

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